Field of the Invention
The invention relates to a fingerprint identification technology and particularly relates to a capacitive fingerprint identification device.
Description of Related Art
A capacitive fingerprint identification device has the advantages of small size and low cost and therefore has been widely used in various electronic devices. The capacitive fingerprint identification device includes a sensing array composed of a plurality of sensing electrodes and uses the capacitor difference, which the sensing electrodes form with respect to ridges and valleys on the finger surface, to obtain a fingerprint image. However, the capacitor difference, which the sensing electrodes form with respect to the ridges and the valleys, is small. For example, capacitors formed by the sensing electrodes with respect to the ridges and the valleys may be merely 0.1 fF (femtofarad) and 1 fF. For this reason, the fingerprint identification device is easily affected by the parasitic capacitors in the environment and cannot accurately identify the fingerprint. As a result, the accuracy of the fingerprint identification device is low.